The invention is directed to humanized antibodies and, more specifically, to humanized antibodies to human 4-1BB.
An extensive body of evidence has unequivocally demonstrated that some degree of immune response against cancer exists in humans and animals. In cancer patients, cellular components of the immune system are able to recognize antigens expressed by tumor cells, such as differentiation or oncofetal antigens, or mutated gene products (S. Rosenberg, Nature, 411:380 (2001)). A number of clinical studies have shown that tumor-infiltrating lymphocytes have favorable prognostic significance (E. Halapi, Med. Oncol., 15:203 (1998); J. Resser et al., Curr. Opin. Oncol., 10:226 (1998); D. Elder, Acta Oncol., 38:535 (1999); L. Zhang et al., New Engl. J. Med., 348:203-213(2003)). Furthermore, clinical results with immunomodulators (bacterial products or biological response modifiers such as cytokines) led to tumor regression in a number of patients (S. A. Rosenberg, Cancer J. Sci. Am. 6 (S):2 (2000); P. Bassi, Surg. Oncol.11:77 (2002); Fishman M, and S. Antonia, Expert Opin Investig Drugs. 12:593 (2003). Despite these responses, immunity against cancer frequently fails to effectively eliminate tumor cells. Among the known causes of immune failure against cancer is the lack of co-stimulatory molecules on tumors, which results in the inability of the tumor cells to effectively stimulate T cells. Recent advances in our understanding of the requirements for tumor antigen recognition and immune effector function indicate that a potential successful strategy to enhance an anti-tumor immune response is providing co-stimulation through an auxiliary molecule.
The current model for T cell activation postulates that for an induction of full activation, naive T cells require two signals: a signal provided through the binding of processed antigens presented to the T-cell receptor by major histocompatibility complex (MHC) class I molecules (signal 1); and an additional signal provided by the interaction of co-stimulatory molecules on the surface of T-cells and their ligands on antigen presenting cells (signal 2) (D. Lenschow et al., Annu. Rev. Immunol., 14:233-258, (1996); C. Chambers et al., Curr. Opin. Immunol., 9:396-404 (1997)). Recognition of an antigen by a naive T cell is insufficient in itself to trigger T-cell activation. Without the second co-stimulatory signal, T cells may be eliminated either by promoting its death or by inducing anergy (A. Abbas et al., Cellular and Molecular Immunology, 3rd ed., 139-170, (1997)).
4-1BB, also referred to as CD137, is a member of the tumor necrosis factor receptor (TNFR) gene family which includes proteins involved in regulation of cell proliferation, differentiation, and programmed cell death (A. Ashkenazi, Nature, 2:420-430, (2002)). 4-1BB is expressed predominantly on activated T cells, including both CD4+ and CD8+ cells, NK cells, and NK T cells (B. Kwon et al., Mol. Cell, 10:119-126, (2000); J. Hurtado et al, J. Immunol. 155:3360-3365, (1995); L. Melero et al., Cell. Immunol. 190:167-172, (1998)). In addition, 4-1BB has been detected on dendritic cells (T. Futagawa et al., Int. Immunol. 14:275-286, (2002); R. Wilcox et al., J. Immunol. 168:4262-4267, (2002); M. Lindstedt et al., Scand. J. Immunol. 57:305-310, (2003)), macrophages, activated eosinophils, and intra-epithelial lymphocytes (K. Pollok et al., J. Immunol. 150:771-781 (1993); D. Vinay et al., Semin. Immunol. 10:481-489, (1998)). Naive, resting T-cells do not express the receptor, which is up-regulated upon activation. Signaling through 4-1BB was demonstrated to induce T-cell proliferation, induction of interferon-gamma (IFN-γ) synthesis, and inhibition of activated cell death in murine and human T-cells (Y. Kim et al., Eur. J. Immunol. 28:881-890, (1998); J. Hurtado et al., J. Immunol., 158:2600-2609, (1997); C. Takahashi et al., J. Immunol., 162:5037, (1999)). The natural ligand for 4-1BB, 4-1BB ligand (4-1BBL), is a member of the TNF superfamily and is detected mainly on activated antigen-presenting cells, such as B cells, macrophages, and dendritic cells (M. Alderson et al., Eur. J. Immunol., 24:2219-2227 (1994); K. Pollok, et al., Eur. J. Immunol. 24:367-374 (1994)) but also in murine B-cell lymphomas, activated T-cells, and human carcinoma lines of epithelial origin (M. DeBenedette et al., J. Immunol. 158:551-559 (1997); H. Salih et al., J. Immunol. 2903-2910 (2000)).
In vivo efficacy studies in mice have demonstrated that treatment with anti-4-1BB antibodies led to tumor regressions in multiple tumor models, indicating the potential use of this therapy for the treatment of cancer. Of note, anti-murine 4-1BB antibodies were shown to induce an immune response against tumors that were poorly or non-immunogenic (I. Melero et al., Nat Med. 3:682-685, (1997); R. Wilcox et al., J. Clin. Invest. 109:651-659, (2002)). Anti-murine 4-1BB antibodies that showed anti-tumor activity were shown to enhance IFN-gamma synthesis in vitro. A number of reports have unequivocally demonstrated that in vivo induction of IFN-gamma by treatment with anti-4-1BB antibodies is critical for the production of an effective anti-tumor immune response (R. Wilcox et al., Cancer Res. 62:4413 (2002); R. Miller et al., J. Immunol. 169:1792 (2002) and studies reported here). Neutralization of IFN-gamma activities significantly reduced the antitumor effects observed with anti-4-1BB antibodies in several tumor models, revealing a correlation between in vitro functional effects, i.e., induction of IFN-gamma, and in vivo anti-tumor efficacy. There is ample in vitro evidence that binding of human 4-BB to its natural ligand or anti-human 4-1BB antibodies produce similar functional effects to that observed with anti-murine 4-1BB antibodies (Y. Kim et al., Eur. J. Immunol. 28:881 (1998); Y. Wen et al., J. Immunol. 168:4897 (2002)). However, most of the anti-human 4-1BB antibodies reported have been raised in rodents which made them unsuitable for human treatment. One report demonstrated that administration of a humanized anti-human 4-1BB antibody in vivo induced suppression of T-cell dependent immunity in nonhuman primates, an effect also observed with anti-murine 4-1BB antibodies (H. Hong et al., J Immunother. 23:613-621 (2000)).
Consequently, based on the roles of 4-1BB in modulating the immune response and the demonstration of efficacy in murine tumor models, it would be desirable to produce anti-human 4-1BB antibodies with agonistic activities that could be used for the treatment or prevention of human diseases like cancer.